Here is a comprehensive list of all the design file dimensions you need to note while uploading your files.
ElementLocationDimensionsFormat and file size
Background imageBranding / Theme / Background image1920 x 1080 pxJPG, JPEG, PNG, GIF; up to 4MB
Webinar logoBranding / Theme / Navbar200 x 80 pxJPG, JPEG, PNG, GIF; up to 4MB
Brand Logo Registration page(template 1)200 x 200 pxPNG; up to 4MB
Banner imageRegistration page / Background carousel / Toggle off Default Background// Upload cover media720 x 344 pxJPG, JPEG, PNG, GIF; up to 1MB
Banner videoRegistration page / Background carousel / Toggle off Default Background// Upload cover media1920 x 1080 pxMP4; up to 4MB
Speaker imagePeople / Speaker / Add speaker300 x 300 pxJPG, JPEG, PNG, GIF